+ ltlo9 - Universiti Teknologi Malaysia

(Pind.l/07)
PSZ19:16
MAtA
UNI
OF THESIS
DECTARAIION
S/O SUBRAMANIAM
Author'sfullnome : RAMESH
Dote of birth
:
171O111972
Title
:
TANKSYSTEM
lN FltLlNGSIAIION
MONITORING
UNDERGROUND
USINGTANKGAUGINGSYSTEM
Acodemic Session: 2OOgl2OOg
I declore thot this thesisis clossifiedos :
E
E
E
CONFIDENIIAL (Contoins
confidentiolinformotionunderthe OfficiolSecret
AcI 1972)*
RESTRICTED
(Contoinsrestrictedinformotionos specifiedby the
orgonizolionwhere reseorchwos done)*
OPENACCESS
I ogree thot my thesisto be publishedos onlineopen occess
(fulltext)
reservesthe rightos follows:
I ocknowledgedthot UniversitiTeknologiMoloysio
TeknologiMoloysio.
l. Thethesisis the propertyof Universiti
Moloysiohosthe rightto moke copiesfor the purpose
2. TheLibroryof UniversitiTeknologi
of reseorchonly.
3. TheLibroryhosthe rightto moke copiesof the thesisfor ocodemic exchonge.
Certifiedby:
SIGNAIURE
OF SUPERVISOR
720111-t0-5339
(NEWrC NO.)
so6.
3l
Apslu zooq
DR.NORHAZII-AN
MD. NOOR
NAMEOF SUPERVISOR
Dote:
)+ ltlo9
pleoseottoch with the letterfrom
or RESTRICTED,
lf the thesisis CONFIDENTAL
the orgonizotionwith period ond reosonsfor confidentiolityor restriction.
"I herebydeclarethat I havereadthis project and in my opinion
this project is suffrcientin termsof scopeandquality for the
awardof the degreeof Bachelorof Civil Engineering".
Signature
Nameof Supervisor : DR. NORHAZILAN MD. NOOR
Date
t1 l4lo4
MONITORING UNDERGROUND TANK SYSTEM IN FILLING
STATION USING TANK GAUGING SYSTEM
RAMESH S/O SUBRAMANIAM
A report submitted in partial fulfilment of the
requirements for the award of the degree of
Bachelor of Civil Engineering
Faculty of Civil Engineering
Universiti Teknologi Malaysia
APRIL 2009
ll
I declare that this project entitled "Monitoring Underground Tank System In Filling
Station Using Tank Gauging System" is the result of my own research except as
cited in the references. This thesis has not been acceptedfor any degree and is not
concurrently submitted in candidature of any other degree.
Signature
Name
Date
: RAMESH S/O SUBRAMANIAM
QT *7P11-2-c)oq
iii
Specially dedicated to my beloved parents
Mr. Subramaniam and Mrs Letchumy
My beloved wife and children
Ms Logiswary, Sasmiitha and Keshaveen
Thank you for your endless love and encouragement
My brothers
Shuraish, Ravi and Prakash
For their support and contribution
iv
ACKNOWLEDGEMENT
I would like to express my sincere gratitude and thanks to my supervisor, Dr.
Norhazilan Md. Noor from the Faculty Of Civil Engineering, University Technology
Malaysia for his generous guidance, cooperation and advises from time to time
throughout the duration of this dissertation. His valuable knowledge and support is
greatly appreciated.
I also take this opportunity to thanks my friends who had contributed
assistance and advice in this study, either directly or indirectly, yet their name are
not cited here. They deserve my greatest gratitude. Million thanks to all.
Last but not least, I would like to thank my beloved wife for her continuous
support, family members and friends, who had given a lot of encouragement and
motivation to complete this research.
v
ABSTRACT
Underground storage tanks are one of the important components in
construction of filling station. It comes in different sizes and capacity. Underground
tanks in filling station are manufactured to ensure safety and integrity accordance to
standards and codes. Many of these underground storage tanks have leakage problem
which is one of the common failure. Most of the under ground tanks fail to detect the
product losses if the tanks are not equipped with monitoring devices. Releases from
a tank that arise from spills, overfills, leakage and piping can cause fires or
explosions that threaten human safety. This study considers the importance of
monitoring system which briefly describes the obligation of filling station owners in
managing underground storage tanks. Studies have been carried out at Shell filling
station located in Klang Valley. A total of forty (40) questionnaires were distributed
to Shell filling station equipped with manual dipping and tank gauging system.
Thirty (30) questionnaires were returned completed out of forty (40) questionnaires
distributed. Comparison of two methods by using manual dipping and tank gauging
system was done. Furthermore, factors contribute to water ingress in underground
tank was also discussed. From the analysis it can be concluded that tank gauging
system is the most effective monitoring system, whereby tank information, water
ingress and product release can be easily detected. It also shows reliability in terms
of safety, efficiency, data accuracy and savings to the filling station in longer run.
The factors contribute to water ingress in tank are caused by uneven driveway level,
human error, construction defects and insufficient preventive maintenance. In
conclusions, the three objectives were achieved and recommendations for
improvement were suggested.
vi
ABSTRAK
Tangki minyak bawah tanah merupakan satu komponen penting bagi struktur
stesyen minyak. Ianya direkabentuk dalam pelbagai saiz dan kapasiti. Tangki
minyak bawah tanah di stesen minyak direkabentuk mengikut kualiti yang
ditetapkan untuk memastikan keselamatan tangki serta kekuatan mengikut
spesifikasi. Kebanyakkan tangki bawah tanah ini masih mengalami kebocoran.
Kebocoran tangki adalah satu masalah lazim yang kerap berlaku. Kebocoran pada
tangki bawah tanah tidak dapat dikesan sekiranya tangki tersebut tidak dilengkapi
dengan sistem pengesan kebocoran. Kehilangan minyak boleh berlaku disebabkan
oleh lebihan pengisian, kebocoran pada dinding tangki serta paip minyak. Ini boleh
menyebabkan kebakaran dan berbahaya kepada manusia. Matlamat kajian ini adalah
untuk mengkaji kepentingan sistem pengesan kebocoran dalam sistem tangki minyak
bawah tanah di stesen minyak. Kajian ini dijalankan di stesen minyak Shell terletak
di kawasan Lembah Klang. Sebanyak empat puluh (40) borang soal selidik telah
disediakan dan diedarkan di stesen minyak Shell yang mempunyai alat pengukur
manual dan elektronik. Daripada jumlah tersebut, tiga puluh (30) borang selidik yang
lengkap telah dipulangkan. Daripada keputusan yang diperolehi, didapati bahawa
alat pengukur elektronik adalah amat berkesan untuk digunakan sebagai alat
pengesan kebocoran, pengukur kandungan minyak dan air di dalam tangki minyak.
Ianya juga berkesan dari segi keselamatan, kecekapan dan kejituan data. Ia juga akan
memberi penjimatan kos dalam jangka masa panjang. Faktor yang mempengaruhi
kemasukkan air di dalam tangki minyak juga dikenal pasti. Ia disebabkan oleh aras
konkrit yang tidak rata, kecuaian manusia, kacacatan pembinaan dan kelemahan
dalam sistem penyelenggaraan. Sebagai kesimpulan, kesemua tiga objektif telah
dicapai dan cadangan untuk pembaikkan juga telah dinyatakan.
vii
TABLE OF CONTENTS
CHAPTER
1
2
TITLE
PAGE
DECLARATION
ii
DEDICATION
iii
ACKNOWLEDGEMENT
iv
ABSTRACT
v
ABSTRAK
vi
TABLE OF CONTENTS
vii
LIST OF TABLES
xi
LIST OF FIGURES
xii
LIST OF SYMBOLS
xiv
LIST OF APPENDICES
xv
INTRODUCTION
1
1.1
Introduction
1
1.2
Problem Statement
2
1.3
Aim and Objectives of Study
3
1.4
Scope of The Study
4
1.5
Importance Of The Study
4
1.6
Research Methodology
6
LITERATURE STUDY
8
2.1
Introduction
8
2.2
Types Of Tanks
9
viii
CHAPTER
TITLE
2.2.1
Single Skin Tanks
9
2.2.2
Double Skin Tanks
10
2.2.3
Steel Tank
11
2.2.4
Glass Reinforced Plastic
12
2.2.5
Composite
12
2.3
Tank Design Criteria
2.4
Maintenance Requirements For Under Storage
2.5
2.7
3
12
Tank System
14
Preventive Maintenance
14
2.5.1
Why Preventive Maintenance Is Importance
15
2.5.2
Preventive Maintenance Program
16
2.5.3
Preventive Of Failures Or Mitigation Of
Failures
2.6
PAGE
16
Tank Leak
17
2.6.1
Catchment Basins
18
2.6.2
Correct Filling Practices
18
Overfill Protection
19
2.7.1
Automatic Shutoff Devices
20
2.7.2
Overfill Alarm
21
2.7.3
Ball Float Valve
22
2.8
Corrosion Of Steel Tank
23
2.9
Summary Of Chapter
24
RESEARCH METHODOLOGY
25
3.1
Introduction
25
3.2
Literature Study
26
3.3
Research Methodology
26
3.4
Data Collection Method
27
3.4.1
Complaints Log
27
3.4.2
Product Loss Investigation Procedure
30
ix
CHAPTER
TITLE
3.4.3
3.5
4
5
Tank Integrity Test
PAGE
32
Tank Monitoring System
34
3.5.1
Dipstick
35
3.5.2
Tank Gauging System
36
3.6
Research Methodology
37
3.7
Data Collection And Analysis
38
3.7.1
38
Average Index (AI)
3.8
Expected Results
39
3.9
Summary Of Chapter
40
DATA ANALYSIS
41
4.1
Introduction
41
4.2
Background Information Of The Respondents
43
4.3
The Level Of Safety Awareness Of The User
45
4.4
Efficiency And Reliability Of The System
47
4.5
Wet Stock Management Accuracy
51
4.6
Cost Management
52
4.7
Water Ingress To Under Ground Tank
55
4.8
Summary
57
CONCLUSION AND RECOMMENDATION
58
5.1
Introduction
58
5.2
Discussion Of The Findings
59
5.2.1
To propose effective detection system to
monitor water ingress and information on
the tank level based on manual and
tank gauging system
5.2.2
59
To determine the cost saving and accuracy
of information on tank level by manual
dipping and tank gauging system
62
x
CHAPTER
TITLE
PAGE
5.2.3 To identify the factors which contribute to
water ingress in underground tank
62
5.3
Implication Of The Study
63
5.4
Limitation Of The Study
64
5.5
Recommendation
64
REFERENCES
66
Appendices A
67
xi
LIST OF TABLES
TABLE NO.
TITLE
PAGE
3.1
Complaints data on water ingress to under ground tank
29
3.2
Plan maintenance schedule for under ground tank testing
32
4.1
Survey results on safety awareness for manual dipping and
tank gauging system
4.2
Effectiveness and reliability results on manual dipping and
tank gauging system
4.3
4.5
48
Survey results on wet stock management for manual
dipping and tank gauging system
4.4
46
51
The average index of the respondents on cost impact for
manual dipping and tank gauging system
53
Water ingress to under ground tank
55
xii
LIST OF FIGURES
FIGURE NO.
TITLE
PAGE
1.1
Research methodology flowchart
7
2.1
Single wall steel under ground tank
10
2.2
Double wall under ground tank
11
2.3
Tank certificate detail
13
2.4
Fill pipe catchment basins
18
2.5
Correct filling practice for under ground tank
19
2.6
Overfill shutoff devices
20
2.7
Overfill alarm system
21
2.8
Ball float valves
22
2.9
Tank corrosion
23
3.1
Call centre help line flow chart for maintenance call
28
3.2
Flow chart for product leak investigation procedure
31
3.3
Microphone and head set used for tank integrity test
34
3.4
Manual dipping to check product volume and water
presence
35
3.5
Tank gauging probe and controller
36
3.6
Research methodology flow chart
37
4.1
Respondents feedback results
42
4.2
Respondents education background
43
4.3
Respondents according to their age group
44
4.4
Respondents according to their sex
45
xiii
FIGURE NO
4.5
TITLE
The average index on safety of using manual dipping
and tank gauging system
4.6
52
Cost management for manual dipping and tank gauging
system
4.9
50
Wet stock management accuracy on manual dipping
and tank gauging system
4.8
47
The average index on effectiveness and reliability of
manual dipping and tank gauging system
4.7
PAGE
54
Factors that contribute to water ingress in under ground
tank
56
xiv
LIST OF SYMBOLS
AI
-
Average index
GRP
-
Glass reinforced plastic
PLIP -
Product leak investigation procedure
UST
Underground storage tank
-
xv
LIST OF APPENDICES
APPENDIX
A
TITLE
A sample of questionnaire
PAGE
67
CHAPTER 1
INTRODUCTION
1.1
Introduction
Underground tank is a stationary device designed to contain an accumulation
of hazardous substance which is constructed of non-earthen materials (for example,
concrete, steel, plastic) that provide structural support. The definition of an under
ground storage tank (UST) is any one or combination of tanks including appurtenant
pipes, lines, fixtures, and other related equipment, used to contain an accumulation
of hazardous substances, the volume of which, including the volume of the
appurtenant pipes, lines, fixtures and other related equipment.
It is ten percent or more beneath the surface of the ground. Hazardous
substances mean petroleum products which are liquid at standard conditions of
temperature and pressure at 60 degrees Fahrenheit. They are material or item that has
the potential to harm humans, animals or the environment. They can act directly or
through interaction with other factors (Jesse C. Ducommun, 2005). Under ground
tanks are one of the important component in construction of filling station with
different in sizes and capacity. Most commonly type of under ground tanks used in
Malaysia are steel and fibre type.
2
Protecting the environment is and will continue to be one of the most
important topics our industry faces during the coming decades. In response to the
need for an environmentally safe underground storage tank, the Double-Wall FRP
Jacketed Steel Tank is one of the finest double-wall tanks available in the market
today, listed with UL and widely used in our country.
1.2
Problem Statement
Throughout the world, the petroleum industry uses most of the underground
storage tanks for filling stations. Underground oil tanks don't last forever. Most have
a life span of twenty to forty years. However, underground tanks installed in the
1970's could deteriorate in a shorter time because less sturdy materials could have
been used at that time in their manufacturer. Underground tanks, so long as they
retain their integrity, provide a safe method for such storage and this has traditionally
been the preferred method for storing petrol at filling stations.
However, they are a history of leaking, often for long periods of time before
signs of contamination or pollution at locations outside the site boundary indicate the
existence of a problem. The main cause has been corrosion of the tank, creating
pinholes which gradually increase in size. The ones of such corrosion is
unpredictable and the detection of the initial stages of a leak almost impossible
without sophisticated detection devices.
Problems with USTs arise when they begin to leak. Motor fuel contains
hydrocarbons and additives that pose health risks to people, animals and plants.
Nature can break down these hydrocarbons through a method called bioremediation.
Unfortunately nature’s work is slow compared to our needs.
3
These dangerous compounds may transmit quickly through soil. These
dangerous compounds may transmit quickly through soil and can find their way
down to an aquifer. In Malaysia, there are population relies to some extent on
groundwater as a source of drinking water. Aquifers are where these drinking water
sources are stored under ground. When aquifer becomes contaminated by hazardous
chemicals the effects can be devastating. Even if people, plants and animals do not
become ill or die, contamination may persist for years and the remediation may cost
millions of dollars.
Previous common practice was to place unprotected steel under ground tanks
and piping in the ground and forget about them. Unprotected steel can be highly
subject to corrosion especially in aqueous environments whereby high water table
presence. Now new tanks and related piping are required to meet federal and state
requirements intended to prevent leakage to groundwater. Tanks which do meet
these requirements must be removed, replaced or upgraded.
Awareness of the problem and new environmental regulations have
prompted companies to provide products that will increase UST safety and the
maintenance system in place will keep tanks integrity last longer. It is for this reason,
together with increased concern for the environment, the industry developed the
double skin storage tank which allows easier detection of leaks and helps prevent
leaked product escaping from the site.
1.3
Aim And Objective Of The Study
The aim of this research is to study on filling station having underground
tank monitoring system using tank gauging system and manual dipping. This study is
carried out on these following three objectives:-
4
i)
To propose effective detection system to monitor water ingress and
information on tank level based on manual and electronic dipping
ii)
To determine the cost saving and accuracy of information on tank
level by manual and tank gauging system
iii)
To identify the factors which contribute to water ingress in under
ground tank.
1.4
Scope Of The Study
This study was confined to the following scopes:
i)
This study to be conducted at single wall steel under ground tank
equipped with electronic dip and manual dip.
ii)
The data collection for analysis will be done at various Shell filling
station located in Klang Valley.
iii)
The comparison of method confined to manual dipping and electronic
dipping.
1.5
Importance Of The Study
This research will benefit the management and end users in terms of
minimizing the risk to environment from pollution and risk of product losses into the
ground. On production site, reliable tanks will be produced to overcome the current
tank leaks issues.
5
By implementation of monitoring system in filling station will help to reduce
the maintenance and station operation cost. Findings from this research will benefit
the management to upgrade the current system to upgraded version and will have a
complete monitoring system for under ground tanks. With this complete system, tank
leaks can be detected at early stage and prevention measures can be taken
immediately by the station operators without having losses and to protect the
environment from polluted.
A study is conducted so that everyone who has the opportunity to read the
research can understand what the researcher is trying to convey. It is important that
the message is conveyed accurately for the readers in order to enhance their
knowledge and capability.
As we have mentioned earlier in the problem statement, with the leak
detection system in place, it can contribute to the saving of operation cost and protect
the environment against any releases of product. When properly installed the
complete system should retain its integrity for the entire duration of its design life.
The research is also to propose to help out all the parties involved to
understand the importance of implementing tank gauging system for all filling
stations compare to manual dipping which can cause damage to the tank wall and
tank leak. This study can also help clients, consultants and manufacturers to optimize
the usage of complete tanks system for all filling station for steel tanks, contribute to
the awareness of safe environment and safe cost operationally.
6
1.6
Research Methodology
The study that carried out focuses on filling station with steel underground
storage tank equipped with dipstick and tank gauging system. Data collected and
making conclusions based on the respondents feedback. To achieve the objectives of
the study, the research methodology is planned and arranged as in Figure 1.1
7
Identify Problem
1. Product spillover from tanks during filling or releases from tank system.
Insufficient system to alarm the station owner.
2. Water ingress into the under ground tanks and no warnings
3. Manual dip is one of the factor contribute to tank fail. Percentage of
accuracy on tank level is very low compare to electronic dipping
Hypothesis
1. To determine effective system to detect tank leak and provide reliable
take information
Objective Of The Study
1. This study to be conducted at single wall steel under ground tank
equipped with electronic dip and manual dip.
2. To determine the cost saving and accuracy of information on tank level
by manual and electronic dipping.
3. To identify the factors which contribute to water ingress in under ground
tank.
1.
Findings
To propose effective leak detection and tank monitoring system
Figure 1.1: Research methodology flow chart
CHAPTER 2
LITERATURE REVIEW
2.1
Introduction
Underground tanks for petroleum products provide a safe means for the
storage of a potentially dangerous and highly polluting liquid. It should be protected
against accidental damage, malicious attack or environmental degradation. It takes
more than equipment to be in compliance and to have a safe facility.
Maintenance of under ground tank systems properly over time will benefit
station operators whereby failure to operate and maintain equipment can lead to new
releases and losses occurred. As the maintenance is part of engineering activity, the
types of maintenance to be adopted are very important in order to achieve high
performance and reliability of the fuel systems.
9
2.2
Types Of Tank
There is variety of types of storage tank available for both above and below
ground. Tanks are generally cylinders and installed horizontally. Some above ground
tanks may be mounted vertically and they may also be slab sided with flat bottoms
and flat or domed tops.
Tanks are commonly manufactured from steel, glass reinforced plastic or
using a combination of steel and plastic or glass reinforced plastic. They may be
single skin or double skin depending on the type and construction and the intended
use. The selection of the tanks should be determined from an assessment of the risks
both to the safety of people and of polluting the environment, (Timm, PR. 1999).
When choosing the type of tank for underground service it is important to
recognize that there are two interested factors that must be considered, first the
configuration of the tank whether it is to be single or double skin, and secondly what
materials are to be used in the construction.
2.2.1
Single Skin Tanks
Constructed in any of the materials by using steel, glass reinforced or
composite. It can pose a potential threat to safety and the environment since if a leak
occurs, product will already have been released into the ground before the loss is
noticed. Figure 2.1 shows the single wall steel tank.
10
Figure 2.1 : Single wall steel under ground tank
2.2.2
Double Skin Tanks
Constructed in any of the materials provided with added protection because
of the ability to contain any releases of product from the primary tank shell and in
addition to allow the inclusion of a monitoring system which will indicate a failure
of either skin as shown in Figure 2.2. Double wall skin tanks pose a very low threat
to safety or the environment if the installation is done properly.
11
Figure 2.2 : Double wall under ground tank
2.2.3
Steel Tank
Steel tanks are prone to corrosion and subsequent failure although coatings
do offer some protection. For single skin steel tanks, the integrity of the coating is of
paramount importance. For double skin steel tanks, the inner skin and inside of the
interstitial space remain unprotected. Tanks are manufactured to BS EN Standards
will be supplied with an appropriate external coating to protect against corrosion.
The degree of protection offered and the operational life for steel tank depends on
the quality of the coating and its integrity. Cathodic protection may also be used to
provide added protection.
12
2.2.4
Glass Reinforced Plastic
Tanks constructed of GRP do not fail to corrosion but their performance
relies particularly on their design and the quality control of the manufacturing
process. Tanks to be used for underground storage of petroleum products should be
manufactured to comply the requirement of BS EN 976 which specifies two different
types of tank requiring different installation standards.
2.2.5
Composite
Tanks manufactured from composite materials are intended to combine the
best qualities of the traditional steel and the later GRP tank. They may be single skin
or double skin and the necessity for any additional protection measures ill be
determined from a consideration of the risks to safety or the environment at a
particular location and the properties of the composite tank itself.
2.3
Tank Design Criteria
In Malaysia, steel tanks are manufactured to ongoing total quality
management to ensure safety and integrity accordance to standards and codes;
•
MS761 – Code of Practice for The Storage and Handling of Flammable
and Combustible Liquids
13
•
BS2594 – Specification for carbon steel welded horizontal cylindrical
storage tanks
•
UL58
– Steel Underground Tanks for Flammable and Combustible
Liquids
All tanks should be a Certificate of Conformity supplied by the manufacturer
to confirm with the requirements of appropriate EN standard. The certificate may
include details of Class, Certifying Authority’s approval number, client job, job
number and site. It also have test operation results identifying normal capacity,
material grade, number of compartments and their capacity, pressure test of skin,
exterior finish, interior finish, thickness of any exterior protective coating, interstitial
space volume and be signed on behalf of the manufacturer as shown in Figure 2.3.
Figure 2.3 : Tank certification detail
Tanks are normally supplied with provision for the connection of fill, vent,
discharge and vapor return lines as well as contents measurement, testing, leak
detection, overfill prevention and inspection or entry cover.
14
2.4
Maintenance Requirements For Underground Storage Tank System
Tank system should be designed, constructed and installed so as to provide
protection to the public and the environment against any releases of product.
Maintenance of this system plays an important role to ensure continues reliability of
system without fail. A well maintained UST system is not a health or environmental
hazard. However if the system is in poor condition or improperly monitored, the
substance contained in the system can leak into and contaminate the surrounding
soil, groundwater and community water suppliers.
Effective maintenance is critical to many operations. It extends equipment
life, improves equipment availability and retains equipment in proper condition.
Conversely poorly maintained equipment may led to more equipment failure and
may more frequent equipment replacement because of shorter life (Broomfield, B.J,
1997).
2.5
Preventive Maintenance
Preventive maintenance is the foundation of the entire maintenance philosophy.
Without having a preventive maintenance for under ground tank system, the
maintenance activities will cost more they should to implement, take longer than
they should to implement and will have a higher probability of failure.
15
Nevertheless, preventive maintenance has some disadvantages which must be
minimized by;
•
Planned maintenance is performed irrespective of the condition of the
building elements. Consequently, a large number of unnecessary tasks will be
carried out on elements that could have remained in a safe and acceptable
operating condition for a much longer time.
•
As a result of human error during the execution of the maintenance task, the
condition of an element may end up worse than it was before.
•
Planned maintenance tasks are usually very demanding in terms of spare
parts and labor.
2.5.1
Why Preventive Maintenance Is important
Many individuals may believe that this type of Preventive Maintenance
program is too expensive or time consuming to implement, especially when there are
advance predictive or reliability techniques that might be employed. The
effectiveness of the preventive maintenance program is determined by the level of
unplanned equipment maintenance that is performed. Unplanned equipment
maintenance id defined as any maintenance activity that is performed with less than
one week of advanced planning (Terry Wireman, 2008).
Unplanned equipment maintenance is commonly referred to a reactive
maintenance. By not considering maintenance analysis during design stage of
building, grievous problems can be caused regarding function, performance, and
16
safety of the system. This can cause a total replacement of the system or an item
might necessitate (Patton, 1988).
2.5.2
Preventive Maintenance Program
The first step of designing a preventive maintenance program is to determine
the critical units and systems in the under ground tank system that will included in
this program. Management knows that having this program cover every item in the
fuel system is not cost effective. There are certain components which are cheaper to
let run to failure than to spend money maintaining. For tank monitoring system, it is
necessary to have preventive maintenance program to keep station in operation at all
time. The critical parts can be accomplished in several ways by the highest amount
of downtime, the highest product sales and the biggest quality problems (Higgins,
L.R. 1988).
2.5.3
Prevention Of Failures Or Mitigation Of Failures
Prevention of failures can be done by taking action to mitigate the
consequences and try to eliminate or minimize the frequency of failures. Once root
cause of failure has been identified the frequency of events can be addressed. Not
doing the correct maintenance on time to the right quality standards can be the root
cause and this is best rectified by changes in work practices and procedures
(V.Narayanan, 2004).
17
Common modes of failures are failures of a population of equipment all of
which is subject to the same failure mode. As with the problem of an entire
population of similar equipment failing within a similar time frame due to neglect of
a preventive maintenance program (NeilB. Bloom, 2005). This situation should be
avoided
2.6
Tank Leak
Leakage of flammable products can also cause potential fire and explosion
hazards. Hazardous substances can escape into the environment through:
•
Spills
•
Overfills
•
Tank corrosion
The regulations regarding underground storage tanks are designed to prevent
spills and overfill caused by bad filling practices, as well as providing procedures for
monitoring and avoiding any tank corrosion that may occur
Many releases at under ground tank come from spill made during delivery.
Spills usually result from human error and can be avoided if everyone involved in
the fuel delivery follows industry standard practices for tank filling. The tanks most
also have the catchment basins to contain the spills. Basically a catchment basin is a
bucket sealed around the fill pipe.
18
2.6.1
Catchment Basins
Catchment basins are also called “spill containment manholes” or “spill
bucket”. Basically, a catchment basin is a bucket sealed around the fill pipe. To
protect against spill, the basin should be large enough to contain what may spill
when the delivery hose is uncoupled from the fill pipe. A typical delivery hose can
hold about 14 gallons of fuel. Basin range in size which capable of holding a few
gallons as shown in Figure 2.4.
Figure 2.4 : Fill pipe catchments basins
2.6.2
Correct Filling Practices
Many releases at under ground tank come from spills. Spills often occur at
the fill pipe when the delivery trucks hose is disconnected. Although these spills are
usually small, repeated small releases can cause big environmental problems. Human
errors cause most spills. Those mistakes can be avoided by following industry
19
standard practices for the tank filling. The correct filling practice is as shown in
Figure 2.5.
Figure 2.5 : Correct filling practice for under ground tank
2.7
Overfill Protection
If delivery drivers or filling station owners make mistakes, a tank can be
overfilled quickly and large volumes can be released at the fill pipe and through
loose fittings on the top of the tank or loose vent pipe. Overfills usually result from
human error and can be avoided if everyone involved in the fuel delivery follows
industry standard practices for tank filling.
Types of overfill protection or devices are;
•
Automatic shutoff devices
•
Overfill alarm
•
Ball float valve
20
2.7.1
Automatic Shutoff Devices
An automatic shutoff device installed in an underground storage tank fill pipe
can slow down and then stop the delivery when the product has reached a certain
level in the tank. This device sometimes simply called a “ fill pipe device” . Figure 2.6
(a) shows one type of automatic shutoff device. Note that the float is down and the
fill valve is open. Figure 2.6 (b) shows the same shutoff device with the float up and
the fill valve closed.
Illustration (a)
Illustration (b)
Figure 2.6 : Overfill shutoff devices
Some automatic shutoff devices work in two stages. The first stage
f=drastically reduces the flow of product to alert the driver that the under ground
tank is nearly full. The driver can then close the delivery valve and still have room in
the underground storage tank for the product left in the delivery hose. If the driver
does not pay attention and the liquid level rises higher, the valve closes completely
and no more liquid can be delivered into the tank leaving the driver with a delivery
hose full of product.
21
2.7.2
Overfill Alarm
Overfill alarms use probes installed in the tank to activate an alarm when the
tank to either 90 percent full or within 1 minute of being overfilled. Either way, the
alarm should provide enough time for the driver to close the truck’s shutoff valve
before an overfill happens. Alarms must be located where the driver can see or hear
them easily. Overfill alarms work only if they alert the driver at the right time and
the driver responds quickly. Remember to put the alarm on an electrical circuit that
is active all the time so that the alarm will always work. Many deliveries are made at
night when the facility is closed. Station operator shall not turn off the alarm when
they turn off the light after working hours. Overfill alarm do not slow down the flow
of product into the UST. They provide the most rapid hose draining capability
relative to other overfill prevention devices. The Figure 2.7 shows the overfill alarm
device use to monitor the overfill.
Figure 2.7 : Overfill alarm system
22
2.7.3
Ball Float Valve
Ball float valve also known as float vent valves are fitted on the bottom of the
vent line and hang down several inches below the top of tank. When the product
level is below the cage, the ball rests at the bottom of the cage and the vent line is
open as shown in Figure 2.8 (a). As the level of the product rises above the bottom of
the cage, the ball floats on the product and rises in the cage. As the delivery
continues, the ball eventually seats in the vent line as shown in Figure 2.8 (b) and
restricts vapor flowing out the vent line before the tank is full. If all tank fittings are
tight, the ball float valve can create enough back pressure to restrict product flow
into the tank which can notify the driver to close the truck’s shutoff valve. However
if the tank has loose fittings sufficient back pressure may not develop and will result
in an overfill.
Figure 2.8 (a)
Figure 2.8 (b)
Figure 2.8 : Ball Float Valves
23
2.8
Corrosion Of Steel Tank
Unprotected underground metal components of the tank system can corrode
and release product through corrosion holes. Corrosion can begin as pitting on the
metal surface as shown in Figure 2.9.
Figure 2.9 : Tank corrosion
Even a small corrosion hole can leak hundreds of gallons of petroleum into
the surrounding environment over a year. In addition to tanks and piping, metal
components can include flexible connectors, swing joints, and turbines. All metal
UST system components that are in contact with the ground and routinely contain
product must be protected from corrosion. All tanks installed must meet one of the
following performance standards for corrosion protection:
•
Tank and piping completely made of non corrodible material, such as
fiberglass-reinforced plastic.
•
Tank and piping made of steel having a corrosion-resistant coating and
having cathodic protection.
24
•
Tank made of steel clad with a thick layer of non corrodible material.
•
Tank and piping are installed without additional corrosion protection
measures provided that a corrosion expert has determined that the site is not
corrosive enough to cause it to have a release due to corrosion during its
operating life and owners or operators maintain records that demonstrate
compliance with this requirement.
•
Tank and piping construction and corrosion protection are determined by the
implementing agency to be designed to prevent the release or threatened
release of any stored regulated substance in a manner that is no less
protective of human health and the environment than the options listed
above.
2.9
Summary Of Chapter
Based on all the relevant information and data from various journals, books
and internet information, there are few factors that contribute to the failure of under
ground steel tank. After analyzing the issues, prevention measures are important in
this study which contributes to the requirements of underground tank system and to
propose best system for the filling station to monitor the fuel system efficiently.
In the following chapter, the methodology of this study would be discussed in
detail.
CHAPTER 3
RESEARCH METHODOLOGY
3.1
Introduction
The purpose of this chapter is to represent the research design, data collection
method, research coverage, sampling, pilot study and methods used in processing the
data. This section is going to review the methods applied in collecting the data to
study on two monitoring system in filling station in terms of safety, effectiveness,
reliability, wet stock management, cost and finally to identify the factors contribute
to water ingress in underground tank. The data collected will be analyzed and it will
then follow by some discussion and suggestion to conclude best practice on
monitoring system in filling station.
26
3.2
Literature Study
Based on the literature review done in chapter 2, most oil tank failures are
due to rust perforation from the inside of the tank. External oil tank rust happens if
there is a heavy corrosion occurred. This means that if you see any indications of
even a pinhole or leak on an oil tank be careful. The steel may be quite thin and can
be easily punctured even though from outside it may look pretty good. Also the
method that is currently in use to get the tank level information which is manual
dipping using dipstick could be one of the factor that contribute to the leak of tank
wall.
Literature review is also known as the secondary data that has been discussed in
chapter two. Sources for the literature review are from text books, journals,
conference paper and internet. A questionnaire was constructed to obtain feed back
from the station operator and followed by data analysis. The data is analyzed and
presented in form of pie chart, bar chart and table for better understanding.
3.3
Research Methodology
Zikmund ( 1997 ) defined research design as a ‘master plan that specifies the
methods and procedures for collecting and analyzing the need information, it is a
framework for the researchers plan of action’. For the purpose of this study and to
achieve the objectives, the questionnaire was formulated based on the filling station
complaints captured through call center. A survey was done to gather the issues and
recommendations which help in developing the questionnaires.
27
Questionnaire was distributed to forty Shell filling station which has both
measuring system in place followed by interviews on ten stations at selected areas of
Klang Valley, as a sampling for overall station in Malaysia. The data that was
collected through questionnaires are analyzed using average index method. Based on
the results, the objective of this study can be achieved and further improvements can
be done in future.
3.4
Data Collection Method
The collection of data for this study was carry out at Shell filling station
relates to sites equipped with dipsticks and tank gauging system. It is also taken into
consideration of stations that having issues on water ingress to the under ground
tank. Few method will be discussed here to elaborate methods used for collection of
data to develop the questionnaires and achieve the research objectives.
3.4.1
Complaints Log
Shell filling station in Malaysia is maintained by a project management
consultant namely Johnson Controls ( M ) Sdn Bhd which has been in operation
since year 2006. All maintenance issues related to filling station will be directed to
the call center based in Petaling Jaya to handle calls related to all emergencies,
breakdowns and damage.
They receive complaints quickly and easily 24 hours a day, 7 days a week
and the professional team of Customer Service Representatives will guide station
28
operators through the information required to resolve the problem while business can
focus on serving the customers. Process flow for complaints from retailers as per
chart shown in Figure 3.1.
Figure 3.1 : Call centre help line flow chart for maintenance call
Each call will be recorded and service numbers are issued to the filling
station for records purposes. At the same time, the escalation is made to the
respective contractor to trouble shoot the problem. Upon completion, fix and respond
time will be reported to call center for job closure. For under ground tanks, water
ingress to the tank will be either detected by the site operator by doing manual
dipping or triggered through the tank aging system. For this case, further
investigation will be carry out to detect the water source by checking the tank system
entirely.
29
Data’s will be gathered through the complaints made and analysis will be
done on station that reported high frequency of water ingress to the tank. Further
investigation will be carry out to the respective tank to confirm the failure
components. Majority of the factors that allow water ingress to the tank is through
the vent line, discharge cap, dipping cap and pipe line connection and lastly if under
ground tank wall fail. Sample of the data from the complaints log as shown in Table
3.1.
Table 3.1 : Complaints data on water ingress to under ground tank
WO no.
Month
WO
status
Vendor
name
Region
5000908125
Apr/08
COMP
Ho Sing
Selangor
5001004005
Jul/08
COMP
Ho Sing
Selangor
5001009685
Jul/08
COMP
Ho Sing
Selangor
5001174818
Dec/08
COMP
Ho Sing
Selangor
5001277719
Mar/09
COMP
EABC
Johor
WO description
tank 1 (regular)
water level 2 inch,
pls rectify and
solve the problem
4 inches water in
tank 1-U92
tank 1 (u92)
contaminated with
water 2.5inch of
water.
T4 AGO
contiminated 3
inches of water
tank1(V Power)
contiminated
more than 2 inch
of water
tank2 and
tank3(Super) 56
litre of water.
Sub-Cas
FA/EQ283
FA/EQ283
FA/EQ283
FA/EQ283
FA/EQ283
30
3.4.2
Product Loss Investigation Procedure
This investigation process will take place if there is a complaint from retailer
on product losses from the tanks. This document sets out the process that shall be
followed when the Product Loss Investigation Procedure escalates from a PLIP A to
a PLIP B. PLIP A have been followed and a product loss has been identified but not
accounted for. From PLIP A findings, further investigation will be done by initiating
PLIP B. This procedure is a site investigation that needs to be carried out to
determine the source of a product loss once the reconciliation procedures required by
PLIP A have been followed and a product loss has been identified but not accounted
for.
While there is some duplication of the PLIP A procedure this is necessary to
ensure those undertaking the on site investigation have a complete picture of the
product loss investigation. The purpose of this document is to provide guidance for a
systematic approach to undertaking the PLIP B investigation.
A process flow
diagram is provided along with a detailed activity list as shown in Figure 3.2.
If the problem has not been resolved by following these steps the final action
is a full system integrity test. If this indicates the system is tight and there is no
explanation for the losses, then the Wet sock Analyst is advised and monitoring of
the site continues. If the test indicates loss of integrity the process escalates to a
PLIP C.
31
Figure 3.2 : Flow chart for product leak investigation procedure
32
3.4.3
Tank Integrity Test
Tank should be checked to confirm their integrity during the lifetime of the
tank. They are tested either during plan maintenance or reactive maintenance. Where
a leak is suspected the tank should be tested using a method appropriate to the
installation. Test methods based on precision testing techniques should be used
wherever possible. Such forms of testing take account of the many uncontrolled
variables which a simple hydrostatic test cannot. They are therefore more reliable
and have a greater probability of identifying a leak or false alarm than the latter.
Generally precision test methods will be certified as complying with the United
States EPA Standard test procedure for evaluating leak detection methods.
For plan maintenance, tanks are being tested with fixed schedule collaborate
with tank age. As per the design life time, tanks should be replaced after 30 years but
most of the cases, tanks are being used until it appears to be leak or fail during tank
integrity test. The plan maintenance schedule in practice for Shell filling station is as
shown in Table 3.2.
Table 3.2 : Plan maintenance schedule for under ground tank testing
33
Precision tests generally fall into one of two broad categories ;
i)
Volumetric methods
Uses techniques which detect and change in the height of liquid in the tank to
define a leaking or tight tank. Typically such tests provide a measurement of
the leak rate.
ii)
Non Volumetric tests
This do not rely on detecting a change in height measurement to determine a
leaking or tight tank and typically provide a pass or fail result. Examples of
this type of test are those applying a vacuum to the tank or those using
chemical trace elements.
Volumetric method are widely used for Shell filling station. The tank is
tested by using Estabrook Ezy 3 equipment consists of a microphone placed in the
ullage of the under ground tank. This microphone is connected to Acoustic Signal
Processor and to head set enabling the test operator to listen to the acoustic sounds in
the tank as shown in Figure 3.3.
34
Figure 3.3 : Microphone and head set used for tank integrity test
Using a motor blower assembly a slight negative pressure is applied to the
tank system, air or water will be down into the tank if leak exists. These acoustic
signals are recognized by a certified testing operator and characterized as an ullage
portion leak or hiss sound or product portion leak or bubble sound. If ground water is
above the tank bottom the conductive water sensor shall be used.
3.5
Tank Monitoring System
All tanks or compartments should be provided with a means for ascertaining
the quantity of product stored. This may be by use of the dipstick supplied with the
tank or by some means of tank contents gauge. This study will be focused on the
having both system in under ground tanks and the benefits of having both system.
35
3.5.1
Dipstick
Dipsticks are a simple means of measuring the height of product in the tank
from which the volume of product is then determined. Dipsticks are used for the predelivery check in order to determine the ullage and by the use of water findings paste
to check for the presence of water as shown in Figure 3.4. Such devices may
introduce volumetric inaccuracies as they are not calibrated for their respective tank
after installation and the coarseness of the graduations leads to a lack of
discrimination in the readings.
Figure 3.4 : Manual dipping to check product
volume and water presence
36
3.5.2
Tank Gauging System
Tank gauges provide an indication of quantity of liquid contained in a storage
tank without the need to access the tank and take manual dip readings. Like
dipsticks, the gauge measures height of product in the tank but by indirect means,
from which the volume of product is then determined. The effects of variations in the
properties of the product and other factors which will have an effect on the
measurement of height and computation of volume can be taken into account
depending on the sophistication of the system used.
This system support a full-range of fuel management needs, continuously
measuring fuel, water and temperature. It is widely used in Malaysia filling station
and so far Shell Malaysia has invested and successfully installed tank gauging
system at 40 filling station in Klang Valley. Figure 3.5 shows the probe and system
controller used in filling station.
Figure 3.5 : Tank gauging probe and controller
37
3.6
Research Methodology
In general this chapter discussed the methods of collecting and analyze data,
distribution of questionnaire survey and interview with filling station operators.
Figure 3.6 shows the research methodology flowchart used for this study.
Figure 3.6 : Research methodology flow chart
38
3.7
Data Collection And Analysis
Data collected method started with the preparation of questionnaire forms.
The questionnaires were distributed manually to filling station and was collected a
day after. The questionnaire was divided into three sections, Section A, Section B
and Section C. Section A will focus on the background of the respondents, Section B
is on the safety, cost, reliability and stock level management of the system and
Section C is focusing on the factors contribute to the water ingress into under ground
tank.
i)
Section A
The respondents information and background will be collected in this
section.
ii)
Section B and C
This section will cover the level of respondents agrees on the statement
which is tabulated in likert scale in the form of;
Strongly Disagree = 1, Disagree = 2, Satisfactory = 3, Agree = 4, Strongly Agree = 5
3.7.1
Average Index ( AI )
The average index is calculated based on the following formula ( Al –Hammed et al;
1996).
Average Index = AiXi
Xi
Ai = constant which represent the proportional of i;
39
Xi = variable which represent the frequent of respondent agreeing with the
I choice
i
= 1, 2, 3, 4,5
To identify the effectiveness and reliability of both system in filling station,
the method of average index using five scale categories to illustrate the priority of
the problem.These five scale categories are as below:
Strongly Disagree = 1, Disagree = 2, Satisfactory = 3, Agree = 4, Strongly Agree = 5
The classification of average index is referring to Abd. Majid and McCaffer
(1997) are as follows;
1 = ‘strongly disagree’
0
average index < 1.50
2 = ‘disagree’
1.50
average index < 2.50
3 = ‘satisfactory’
2.50
average index < 3.50
4 = ‘agree’
3.50
average index < 4.50
5 = ‘strongly agree’
4.50
average index < 5.00
3.8
Expected Results
From this study, the anticipated respond from the respondents would indicate
the significance of all the identified challenges. After analyzing the data, the author
expect that the tank gauging system will contribute the economical savings and
provides benefits to station operations in terms of accuracy of tank level information
, safety and leak detection system. Factors contribute to water ingress in
underground tank also is expected to identify.
40
3.9
Summary Of Chapter
The research methodology has been identified. The research consideration,
approach of information collection has been clarified and substantiated to ensure
alignment with the objectives of this study. The findings of analysis and discussion
would be discussed in Chapter 4.
CHAPTER 4
FINDINGS AND ANALYSIS
4.1
Introduction
This study focuses on operative Shell filling station in Klang Valley. From
the literature review and interview with few station operators, a set of questionnaires
were prepared for the respondents to obtain feedback on manual dipping and tank
gauging system. The respondents were the retailer of filling station who has been in
the business for more than ten years.
A sample size of forty respondents was chosen as target and a set of forty
questionnaires were printed and distributed. The questionnaires were distributed to
the filling station equipped with dipstick and tank gauging system with station
location at hundred km in radius from city center. The questionnaires were given a
day before taken back as most of the retailers are busy with their own schedule.
42
From the survey, only thirty out of forty questionnaires were returned and the
analysis was done based on the available data as shown in Figure 4.1. Ten
questionnaires were not returned because of misplaced and some of them were in out
station. An example of the questionnaire is shown in Appendix A.
Respondents feedback
Questionanires
not returned
25%
Completed
questionaires and
returned
75%
Figure 4.1 : Respondents feedback results
The questionnaire was divided to specific category which compares the
manual dipping system and tank gauging system by taking below criteria into
consideration.
•
Safety of the equipment when handling time
•
Efficiency and reliability of the system
•
Accuracy in wet stock management
•
Cost of operation
•
Factors contributes for water ingress to under ground tank
43
4.2
Background Information Of The Respondents
The questionnaire was divided into three sections. The first section will focus
on age, sex, highest education and their position. The results are shown in figure 4.2,
4.3 and 4.4. From figure 4.2, the results shows that 47% of the respondents are after
SPM, 38% are Diploma holders and 15 % are Degree holders. None of them have
higher education back ground.
Re s ponde nt's qualification
Degree
35%
Master or
Phd
0%
SPM
34%
Diploma
31%
Figure 4.2 : Respondents education background
Figure 4.3 shows that 60% of the respondents are between the age group of
30-49 years old, 27 % are between the age group of 50-69 years old and 13%
between the age group of 18-29 years old. Those of 30-49 years old are mostly after
SPM holders and some having Diploma. For age between 50-69, there are also
combination of SPM, Diploma and Degree holder.
44
Respondent's age
50 -69
27%
18 - 29
13%
30 - 49
60%
Figure 4.3 : Respondents according to their age group
Figure 4.4 shows that 83% of the respondents are male and 17% are female.
The highest number on male respondents is because of the risk handling the business
is high and it is always a male who be the person in charge.
45
Re s ponde nt's ge nde r
Female
17%
Male
83%
Figure 4.4 : Respondents according to their sex
4.3
The Level Of Safety Awareness Of The User
The objective is to seek opinion from the respondent on the level of safety
awareness while handling both systems in filling station. Based on the questionnaire,
the results obtain as shown in Table 4.1.
46
Table 4.1 : Survey results on safety awareness for manual dipping and tank gauging
system
Manual Dipping
Scale
No
Safety Awareness
1
2
3 4
Total
5
No of respondents
Average
Rank
Index
Safety of person taking the
1
reading is high and secured
9
9
8 4
0
30
2.33
2
6
11
7 6
0
30
2.43
2
Product over fill can be
2
easily detected
Tank Gauging System
Scale
No
Safety Awareness
1
2
3
4
5
Total
No of respondents
Average
Index
Rank
Safety of person
taking the reading is
1
high and secured
0
4
3
10
13
30
4.07
5
0
0
0
10
20
30
4.67
5
Product over fill can
2
be easily detected
The management of Health and Safety Regulations are also relevant and
require for all employers and self-employed persons to asses the risks to workers. By
performing manual dipping, the person needs to remove the dip cap of the tank to
measure the volume of the product in the tank. From the table, respondents are
disagree on overfill prevention by manual dipping compare to tank gauging system
with an average of 2.43 for manual dipping and 4.67 for tank gauging system. This
means, tank gauging system will trigger the operator if there is an overfill and not for
the manual dipping. Tank gauging system has the functionality of built in alarm
system to prevent from overfill.
47
On the safety perspective, results shows that the average index for tank
gauging system is 4.07 and 2.33 for manual dipping. This means, conducting product
level check by using dipsticks is always at high risk if it is not properly trained. It
shows that by using tank gauging system to get tank level information, the risk can
be eliminated and there is no requirement to access under ground tank. Figure 4.5
shows the average index of safety awareness of using dipsticks and tank gauging
system during tank level measurement.
5.00
4.50
4.00
3.50
3.00
2.50
2.00
1.50
1.00
0.50
0.00
4.67
4.07
2.33
2.43
Manual Dipping
Tank Gauging System
Safety
Overfill detection
Figure 4.5 : The average index on safety of using manual dipstick
and tank gauging system
4.4
Efficiency and reliability of the system
The objective is to find the efficiency and reliability on manual dipping and
tank gauging system. Based on the questionnaire, the analysis was done and the
results are as shown in Table 4.2.
48
Table 4.2 : Effectiveness and reliability results on manual dipping and tank gauging
system
Manual Dipping
No
1
2
3
4
5
6
7
8
9
Efficiency & Reliability
Of System
Product losses can be
easily detected
Trouble shooting can be
done fast when found data
discrepancy
Weather factor contributes
when taking the readings
Probes / Dipsticks having
different type and provide
different reading
Possibility having tank
leak due to miss handling
of the system
Easy to handle and
manageable on live site
Water presence in tank can
be detected easily
Chances of using wrong
size of dipstick/probe to
measure product level is
high
Frequency of failure or
down time is high
Scale
1 2 3 4 5
No of respondents
Total
Average
Rank
Index
1
8
13
8
0
30
2.93
0
5
17
8
0
30
3.10
0
5
15 10
0
30
3.17
1
3
15 11
0
30
3.20
0
1
3
10 16
30
4.07
1
3
15 11
0
30
1.70
10 17
3
0
0
30
1.77
1
5
9
15
0
30
3.27
0
3
12 15
0
30
3.40
3
3
3
3
4
2
2
3
3
Tank Gauging System
No
1
2
3
4
5
Efficiency & Reliability
Of System
Scale
1 2 3 4 5
No of respondents
Product losses can be
easily detected
0 0
Trouble shooting can be
done fast when found data
discrepancy
0 0
Weather factor contributes
when taking the readings
16 11
Probes / Dipsticks having
different type and provide
different reading
7 9
Possibility having tank leak 14 14
Total
Average
Index
Rank
2 14 14
30
4.40
4
1 13 16
30
4.50
5
3
0
0
30
1.57
2
8
2
4
0
2
0
30
30
2.50
1.40
3
1
49
6
7
8
9
due to miss handling of the
system
Easy to handle and
manageable on live site
Water presence in tank can
be detected easily
Chances of using wrong
size of dipstick/probe to
measure product level is
high
Frequency of failure or
down time is high
0
0
0 14 16
30
4.53
5
0
0
4 15 11
30
4.23
4
16 10 4
0
0
30
1.60
2
10 10 8
2
0
30
2.07
2
From the results, its shows product losses in tank is hardly can be detected by
manual dipping as per average 2.93 and 4.40 for tank gauging system. For the
trouble shooting in case of data discrepancy, tank gauging system with average of
4.50 and 3.10 for manual dipping. This means tank gauging system can trace back
the data and findings can be done.
Weather is one of the factor can cause discrepancy in getting correct tank
information at specific time. Average index for manual dipping shows 3.17 and 1.57
for tank gauging system. This means during heavy rain, manual dipping cannot be
carry out at site whereby tank gauging system can provide the information regardless
of weather condition.
Defective dipstick or probe can give wrong information to the product
volume. From the results, the average for manual dipping is 2.80 and 2.50 for tank
gauging system. Both have significant failure if it is not properly maintain. One of
the causes of tank leak is due to mishandling of dipstick during manual dipping
which shows average of 4.07 compare to 1.40 for electronic dipping. Frequency of
dipping in longer term can damage the tank base for steel tank. Person who did the
dipping should be well trained and strictly follow rules.
50
Tank gauging system is easy to handle compare to manual dipping. Tendency
to make error is high as average shows 1.70 using dipsticks. For water detection,
both systems can detect water presence as shown the average of 4.23 for tank
gauging system and 1.77 for manual dipping. This means, tank gauging system can
detect water presence efficiently with alarm warning. By using manual dipping, the
water presence can be only detected during the daily dipping process.
Chances of using wrong size of dipstick for dipping an average of 3.27
compare to electronic dipping method at average of 1.60. The down time for both
systems seems to be not much different. Figure 4.6 shows the average scores for
manual dipping and tank gauging system.
Figure 4.6 : The average index on effectiveness and reliability
of manual dipping and tank gauging system
51
4.5
Wet stock management accuracy
Wet stock reconciliation is the management of liquid products at filing
station. The theory is the same as for stock management because it measure how
much is delivered, how much is sold and how much is left. By comparing these three
amounts, retailer can identify any losses and deal with team accordingly. The
management of stock wet stock is made harder because fuels are usually stored
underground. This means that filling station should have a good measurement
system which can deploy by dipstick or gauges.
Based on the results shown in Table 4.3, the respondents have satisfactory
level on manual dipping and strongly agree on tank gauging system. This means, a
significant positive approach in using tank gauging system compare to manual
dipping.
Table 4.3 : Survey results on wet stock management for manual dipping and tank
gauging system
Manual Dipping
No
Wet Stock Management
1
2
Fuel ordering can be done
easily and accurate
Accuracy of wet stock is high
Scale
1 2
3
4 5 Total Average Rank
Index
No of
respondents
0 1
0 2
25
28
4 0
0 0
30
30
3.10
2.93
3
3
Tank Gauging System
No
1
2
Wet Stock Management
Scale
1 2 3 4 5
No of
respondents
Fuel ordering can be done
easily and accurate
0 0 5 5
Accuracy of wet stock is high 0 0 0 5
20
25
Total
30
30
Average
Rank
Index
4.50
4.83
5
5
52
From the Table 4.3, respondent’s opinion is that the fuel ordering by using
both systems still can be done with average of 4.50 for tank gauging system and 3.10
for manual dipping. For accuracy of tank information, tank gauging system is
producing high accuracy with average 4.83 compare to 2.93 on manual dipping.
Figure 4.7 below shows the average index on wet stock management accuracy for
manual dipping and tank gauging system.
6
5
4
4.50
3.10
3
4.83
2.93
Manual Dipping
Tank Gauging System
2
1
Wet
stock
accuracy
Fuel
ordering
0
Figure 4.7 : Wet stock management accuracy on manual dipping
and tank gauging system
4.6
Cost Management
The objectives is to determine the handling cost for both system which can
determine cost saving for the retailer in long term business. From the respondents
results table 4.4, it shows that the average index of handling manual dipstick is at
rank 4 and for tank gauging system at average at rank 2. This means for manual
dipping, the cost is high in terms of manpower, storage, wear and tear and damage to
the equipment. Less cost contributes to manage the tank gauging system as it is only
impact at initial of purchasing process.
53
For tank gauging system, value of the product volumes are certainty whereby
uncertainty lost of product volume can be eliminated. It is also reduces the margin of
error, which means reduced uncertainty during transfer control or verification,
inventory management and loss control. Figure 4.8 shows cost effective management
on manual dipping and tank gauging system.
Table 4.4 : The average index of the respondents on cost impact for manual dipping
and tank gauging system
Manual Dipping
Scale
No
Cost Of The System
1
2
3
4
5 Total
No of respondents
1
Index
Rank
The maintenance and
equipment cost is high
2
Average
1
4
3
18
4
30
3.67
4
0
3
6
20
1
30
3.63
4
1
6
3
18
2
30
3.47
3
0
2
3
22
3
30
3.87
4
1
0
5
24
0
30
3.73
4
Required additional
resources to conduct the
checking and verify data
3
The equipment is taking
space for storage and not
user friendly
4
Wear and tear is high and
need frequent replacement
5
Damage to equipment /
material cost is high
54
Tank Gauging System
Scale
No
Cost Of The System
1
2
3
4
5
Total
No of respondents
Average
Index
Rank
The maintenance and
1
equipment cost is high
2
Required additional
15
12
3
0
0
30
1.60
2
20
10
0
0
0
30
1.33
1
12
18
0
0
0
30
1.60
2
11
19
0
0
0
30
1.63
2
10
18
2
0
0
30
1.73
2
3.87
3.73
resources to conduct the
checking and verify data
The equipment is taking
space for storage and not
3
user friendly
Wear and tear is high and
need frequent
4
replacement
Damage to equipment /
material cost is high
3.63
3.47
1.63
1.73
Equipment damage / repair
1.33
1.60
Wear and tear
Manual Dipping
1.60
Storage of equipment
3.5
3
2.5
2
1.5
1
0.5
0
3.67
Resources
4.5
4
Maintenance cost
5
Tank Gauging System
Figure 4.8 : Cost management for manual dipping and tank gauging
system
55
4.7
Water Ingress To Under Ground Tank
The objective is to determine the factors that contribute to water ingress in
under ground tank. There are many ways water gets in to the under ground tanks and
one of it will be due to installation failure. From the respondents feedback as shown
in Table 4.5, the results shows the highest ranking is due to dip cap was not closed
properly with average 4.63 and unevenness of driveway level during construction
with average 4.50. This mean, above tank driveway or concrete surface is not design
to divert the heavy fall rain water from getting into the tank sump. Failure of
removing water from tank sump could allow water ingress to the tank through the
dip riser.
Table 4.5 : Water ingress to under ground tank
No
Water Ingress To
Under Ground Tank
Scale
1 2 3
4
5
Total
No of respondents
Average
Index
Rank
Water ingress through
the dip cap due to
negligence of the person
1
performing the check
0 0 5
10
15
30
4.33
4
0 0 1
9
20
30
4.63
5
0 0 4
10
16
30
4.40
4
0 0 6
8
16
30
4.33
4
Dip cap and discharge
cover was not properly
2
closed or defective
Constructed fiber sump
at tank man way is not a
3
water tight
Vent pipe cap is not
properly maintained or
4
never maintain at all
5
Concrete surface above
tank is not design to
56
divert rain water from
going into the tank
0 0 3
9
18
30
4.50
5
sump
Follows by negligence of person conducting the tank level check with
average of 4.33 and defects during construction period during installation of fiber
sump with average of 4.40 has also contributed to water ingress. This is due to non
standard specification and human error. Poor maintenance of vent pipe and missing
vent pipe cap allow water ingress to under ground tank with average of 4.33. Figure
4.9 shows the average index for water ingress to under ground tank.
4.63
4.50
Average
Index
4.40
Concrete surface above tank
Maintenance of vent pipe
Tank fiber sump
4.33
Discharge cap
4.33
Water ingress through the dip
cap
4.7
4.65
4.6
4.55
4.5
4.45
4.4
4.35
4.3
4.25
4.2
4.15
Figure 4.9 : Factors that contribute to water ingress in under ground
tank
57
4.8
Summary
The questionnaires seeks information on the back ground of the respondents,
their level of knowledge in tank monitoring system, cost effectiveness, reliability of
the system and factors contribute to water ingress to under ground tank.
CHAPTER 5
CONCLUSION AND RECOMMENDATION
5.1
Introduction
This final chapter concludes by giving a comprehensive discussion on the
findings and highlighting points derived from the study. It begins by giving the
recapitulation of the study, discussion of the findings and then a brief discussion of
implications of the study. Finally this chapter closes with the limitation of the study
that paves the way for future study and a conclusion.
From the study that has been carried out, there are 3 objectives were
identified. The first objective is to propose effective detection system to monitor
water ingress and information on tank level based on manual dipping and tank
gauging system. The second objectives is to determine the cost saving and accuracy
of information on tank level by manual and electronic dipping. The third objective is
to identify the factors which contribute to water ingress to under ground tank.
59
The statistical method were used to explain the average scoring for each
category in Chapter 4 by obtaining data from the questionnaires distributed to forty
filling station. Furthermore, the literature review in Chapter 2 helps a lot in
completing this thesis. As a conclusion, the objectives of this study have been
successfully achieved.
5.2
Discussion Of The Findings
Detailed discussion of the research objectives obtained from the results of
chapter 4. The conclusion from the study can be derived and grouped into three
categories according to the objectives as follow;
5.2.1
To propose effective detection system to monitor water ingress and
information on tank level based on manual and electronic dipping
There were 3 different key points in questionnaires that have been formulated
to obtain feed back from the respondent in terms of safety awareness, efficiency of
the system and wet stock management. The following has been concluded;
i.
Safety awareness
The risk of conducting manual dipping by using dipstick is higher compare to
tank gauging system. Results shows, risk of the person who use dipstick to perform
the tank level check is high and dipstick must be made of non-sparking material to
60
avoid explosion. Before tank dipping was carry out, the area must be barricaded with
reflective cons and signage for high visibility to customers. During the dipping
process, no gadgets should carried by the performer which can cause ignition or
sparks.
Tank gauging systems use monitors permanently installed in the tank. These
monitors are linked electronically to a nearby control device to provide information
on product level and temperature. During a test period of several hours, when
nothing is put into or taken from the tank, the ATG automatically calculates changes
in product volume that can indicate a leaking tank. According to the respondents,
there will be no threat of risk by using this system as the controller will be placed in
the office area
ii)
Efficiency and reliability of system
Dipsticks are made with different type of material available in the market. If
the dipstick is wooden, it must be varnished to prevent petrol creeping up the stick
above the actual level in the tank this preventing a false reading. The dipstick should
be clearly marked to indicate the quantity measured starting with zero at the bottom.
The end of the dipstick must not be worn or cut off and the dipstick should not be
warped. There will be always a high chance that the tank level is taken wrongly.
Poor understanding of the scales and defects on the dipsticks can cause discrepancy
on wet stock.
By using dipstick, it is only liable to measure the fuel level and water
presence in the tank. Failure of conducting daily dipping will have high risk of water
presence without warning. Water will get in to the vehicle will create losses to the
filling station. Unlikely product loss cannot be detected in advance.
61
Tank gauging system can measure temperature at corrected height, volume
mass and density with a single sensor probe. It can also measure water level and has
an independent high alarm. This system may also interface with other equipment and
capable of providing automated stock control, overfill prevention and leak detection
information.
The advantages of tank gauging systems are;
•
Centralized monitoring of equipment which find problem easily, remote
diagnostics and instruct local repair crew.
•
Eliminate human error in paper works, product transfer and theft
•
Timely reporting by viewing the report at one glance, correct the error before
compound and respond to changing needs.
ii)
Wet stock management
Form the respondent’s results, the accuracy level of tank information by
using manual dipstick is low and tendency of reporting product loss is high.
Monitoring of stock level in under ground tank by manual dipping needs a
competent person and understands the risk conducting the check. Failure of
following the procedure may provide falls reading and dispute in product ordering.
Based on the results, tank gauging system provides high accuracy of data on
tank information which helps the station retailer to place order at high confidents.
The product level can be obtained at any point of time without accessing the tank to
measure manually. Data can be easily extracted that was stored in system for month
end closure.
62
5.2.2
To determine the cost saving and accuracy of information on tank level
by manual and tank gauging system
From the results, can be concluded that the cost to maintain manual dipping
is high compare to tank gauging system. Manual dipping incurs additional cost in
term of man power, storage, maintenance and wear and tear. This does not make cost
effectiveness in longer term. The total number of dipstick in filling station is depends
on number of under ground tank whereby each tank will have one dipstick.
Based on the results, the tank gauging system does not required resources to
measure the product level as it is automatically will provide information when is
required. This system equipped with probes and controller which the initial cost is on
equipment and installation. The probes are installed permanently in under ground
tank which does not required to remove for fuel check. In this case, damage to the
equipment is minimized and provides cost effectiveness.
5.2.3
To identify the factors which contribute to water ingress in under
ground tank
To achieve this objectives, there are five factors has been successfully
identified and formulated into questions. Based on the results, the water ingress to
the tank from driveway has the highest average index which shows a high percentage
of poor quality work during the construction period. The driveway level should be
designed to prevent rain water from seeping in to the dipping sump and tank sump so
that water ingress to sump can be avoided.
63
From the results, failure to close the dip cap after manual dipping will also
allow water ingress to under ground tank. It is a mandatory to close the dip cap and
discharge cap and ensure those caps are properly locked. Defective caps should be
replaced with new cap. The possible other location that water can ingress is from the
vent pipe when the vent pipe cap is missing. Chances of water ingress from top of
the under ground tank can be minimized if the identified factors are properly
managed.
5.3
Implication Of The Study
The findings of this study have a number of important implications especially
for station operators that intend to improve on the monitoring system and upgrade
the traditional way of dipping to electronic type. Besides that the station operators
have to make sure that they can improve the knowledge and awareness of having
both systems to help to safe the environment. If negligence occurred, product leak to
the ground can happen and without a detection system, there will be no warning sign
to the station retailer on product release.
In any filling station, a tank monitoring system should be able to detect leaks
and measure water level in tank. Not many of the filling stations are aware on such
system and advantages of monitoring system. Majority of the filling station operators
believe that the manual dipping still give the best reading, easy to handle and give
less trouble but in reality monitoring system gives high accuracy of tank information.
64
5.4
Limitation Of The Study
There were many challenges faced during the process of getting back the
questionnaires. The station which is located in a distance and lack of cooperation
from the retailer slow down the process of getting data on time. Responder who does
not understand the questionnaires has difficulty to answer and more time spend to
explain the scope. Besides that station retailer are not willing to share information on
the issues that currently in place. They also do not want to share the information on
future planning of the monitoring system which has caused certain contradiction to
these studies.
5.5
Recommendation
Based on the study, suggestions have been made in order to assist station
retailer as stated below;
i)
Station operators shall attend training to gain more exposure on
current technology and understand the importance of the tank
monitoring system for leak prevention.
ii)
Improve the safety awareness during manual dipping and suggest to
attend safety training before performing the task.
iii)
Recommend all filling stations to be equipped with monitoring
system to improve wet stock management and to avoid discrepancy of
data by manual dipping.
65
iv)
Condition and the size of dipstick in each under ground tank for
station without tank gauging system must be consistently checked by
the station operator and replace if necessary.
v)
Water ingress to tank sump and underground can be minimize if extra
measures taken during driveway works at tank farm, faulty dip cap to
be consistently checked and vent pipe cap required frequent
maintenance.
vi)
Suggest to roll out preventive maintenance program for underground
tank system.
66
REFERENCES
Abd Majid and McCaffer
(1997). American Society of Civil Engineers, US:
McGraw Hill Inc
Broomfield, B.J. (1997), Management program for underground storage tanks,
New York, The Dryden Press
Jesee C.Ducommun. (2005), BP Process Safety Series, Hazardous Substances In
Refineries, UK, Institution of Chemical Engineers
Timm, PR. (1999), Guidance For The Design, Construction, Modification And
Maintenance Of Petrol Filling Stations, IPEA, IP, US: McGraw Hill Inc
Hasnan Abdullah , Pengurusan Penyelangaraan B.E.Thesis. University Teknologi
Malaysia; 1994
Higgins,L.R. (1988), Maintenance Engineering Handbook, 4th Edition, New York,
McGraw-Hill
Lee, Kiang, Q. (1999), Facilities Management and Maintenance : The Way Ahead
into the Millennium, Singapore, Mc Graw-Hill inc
Logendran s/o Subramaniam, Fire Safety In Tall Building B.E.Thesis. University
Teknologi Malaysia; 2006
Neil B.Bloom. (2005), Reliability Centered Maintenance, New York , Mc GrawHill,inc
Patton, Joseph D. Jr (1988), Maintainability and Maintenance Management,
Instrument Society of America, North Carolina, U.S.A
Terry Wireman. (2008), Preventive Maintenance. New York, Industrial Press.
V. Narayanan. (2004), Effective Maintenance Management , Risk and Reliability
Strategies, New York, Industrial Press
Zikmund, W,G.(1997), Business Research Method. 5Th Edition. New York, The
Dryden Press
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APPENDIX A
A Sample Of Questionnaire
68
69
70
71